1. Field of the Invention
The present invention relates to image sensing apparatus such as still cameras, video cameras and television cameras and, more particularly, to an image sensing apparatus suitable for underwater photography.
2. Description of the Related Art
In recent years, as the number of persons who enjoy scuba diving has rapidly increased, the number of persons who perform underwater photography has also increased. As is known, conventional image sensing apparatus for underwater photography merely utilizes waterproofed combinations of cameras and accessory parts (for example, a video light unit). In practice, a generally-used type of camera-integrated VTR (video tape recorder) is accommodated in a waterproof case. The waterproof case consists of a housing which can be separated into two housing elements so that the camera-integrated VTR can be freely put into and taken out of the waterproof case. Both housing elements can be coupled to each other by a watertight structure such as an 0-shaped ring.
In scuba diving, water-depth information is one of the most important kinds safety information for persons who go down to relatively great depths in water. In general, waterproof cameras are designed and manufactured so that they can withstand water pressures not exceeding the standard values specified in their written specifications, and there is no guarantee that they can withstand water pressures exceeding such standard values. For this reason, a user must always be careful to use a waterproof camera within a pressure range not exceeding the withstand (maximum) pressure of the waterproof camera, and water-depth information is similarly important for the waterproof camera.
Currently, wrist-watch types of water-depth meters are commercially available, and if the user utilizes such a water-depth meter, he can confirm water depths at any time. However, if the user is to confirm a water depth during underwater photography, he must take his eye away from a viewfinder and view the indication of the water-depth meter. If he is absorbed in the photography, he may forget to confirm water depths. Otherwise, he may be hindered from concentrating on the photography due to anxiety about water depths.
During scuba diving, it is necessary to regularly confirm the remaining amount of air in a compressed-air cylinder. However, while the user is performing underwater photography, he is apt to be absorbed in the photography to such an extent that he forgets to confirm the remaining amount of air in the compressed-air cylinder. This is extremely dangerous.
In addition, since it is impossible to replace a battery or a magnetic tape used as a recording medium, the user needs to go up to the surface of water.